U.S. patent number 3,890,974 [Application Number 05/480,523] was granted by the patent office on 1975-06-24 for disposable absorbent article containing slitted hydrogel film.
This patent grant is currently assigned to Union Carbide Corporation. Invention is credited to Theodore F. Kozak.
United States Patent |
3,890,974 |
Kozak |
June 24, 1975 |
Disposable absorbent article containing slitted hydrogel film
Abstract
Disposable absorbent articles are disclosed which include a
topsheet, a liquid impermeable backsheet, and a hydrophilic,
substantially water insoluble film disposed between the topsheet
and the backsheet. The film contains a plurality of straight slits,
of specific length, whereby liquid contacting the film causes the
film to swell and to thereby open said slits to permit passage of
the liquid therethrough.
Inventors: |
Kozak; Theodore F. (Peekskill,
NY) |
Assignee: |
Union Carbide Corporation (New
York, NY)
|
Family
ID: |
23908286 |
Appl.
No.: |
05/480,523 |
Filed: |
June 18, 1974 |
Current U.S.
Class: |
604/368; 604/374;
602/47; 604/378 |
Current CPC
Class: |
A61F
13/53713 (20130101); A61F 13/51121 (20130101); A61L
15/60 (20130101); A61F 13/512 (20130101); A61F
13/53704 (20130101); B32B 27/32 (20130101); A61F
13/534 (20130101); A61F 13/51305 (20130101); B32B
27/06 (20130101); A61F 13/53752 (20130101); B32B
27/00 (20130101); B32B 27/16 (20130101); B32B
27/12 (20130101); B32B 27/285 (20130101); B32B
3/266 (20130101); B32B 7/12 (20130101); B32B
2262/062 (20130101); A61F 2013/530635 (20130101); B32B
2307/31 (20130101); B32B 2307/7265 (20130101); A61F
2013/53782 (20130101); B32B 2307/728 (20130101); B32B
2555/02 (20130101); A61F 2013/51409 (20130101); B32B
2307/73 (20130101); A61F 2013/53445 (20130101); B32B
2323/04 (20130101); B32B 2307/716 (20130101); B32B
2307/726 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A61L 15/16 (20060101); A61L
15/60 (20060101); B32B 27/00 (20060101); A41b
013/02 () |
Field of
Search: |
;128/296,287,284,156,286,287,29R,29W,29P |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Medbery; Aldrich F.
Attorney, Agent or Firm: Vicari; C. J.
Claims
What is claimed is:
1. A disposable absorbent article for placement adjacent to the
body, including:
a. a hydrophobic liquid permeable topsheet for placement adjacent
to the body;
b. a liquid impermeable backsheet; and
c. a hydrophilic, substantially water insoluble film disposed
between said topsheet and said backsheet, said film containing a
plurality of slits of from about 1/6 to 3/8 inch in length, whereby
liquid contacting said film causes the film to swell thereby
opening said slits to permit passage of liquid therethrough.
2. The disposable, absorbent article of claim 1 wherein said
hydrophilic, substantially water insoluble film is selected from
the group consisting of irradiated polyalkylene oxide, polyvinyl
pyrrolidone, polyacrylic acid, and mixtures thereof.
3. The disposable, absorbent article of claim 2 wherein said
hydrophilic, substantially water insoluble film is irradiated
polyethylene oxide.
4. The disposable, absorbent article of claim 3 wherein said
article includes a layer of hydrophilic, absorbent material
intermediate said film and said backsheet.
5. The disposable, absorbent article of claim 3 wherein said
article includes a layer of hydrophilic, absorbent material on each
side of said film.
6. A disposable diaper comprising in combination, the hydrophobic
topsheet, the substantially liquid impermeable backsheet, and the
hydrophilic substantially water insoluble film as defined in claim
1 wherein the topsheet and backsheet are of substantially the same
dimension and being at least partially adhered to each other around
their periphery to form an integrated diaper structure having said
film substantially enclosed and sandwiched between the topsheet and
the backsheet.
7. A disposable diaper as claimed in claim 6 wherein said
hydrophilic, substantially water insoluble film is selected from
the group consisting of irradiated polyalkylene oxide, polyvinyl
pyrrolidone, polyacrylic acid, and mixtures thereof.
8. A disposable diaper as claimed in claim 7 wherein said
hydrophilic, substantially water insoluble film is irradiated
polyethylene oxide.
9. A disposable diaper as claimed in claim 8 wherein said diaper
includes a layer of hydrophilic, absorbent material intermediate
said film and said backsheet.
10. A disposable diaper as claimed in claim 6 wherein said film
contains a plurality of slits of from 2/16 to 5/16 inch in
length.
11. A disposable diaper as claimed in claim 6 wherein said film
contains from 2 to about 24 slits per square inch of film area.
Description
The invention relates to disposable absorbent articles such as
diapers, incontinency pads, and the like.
The use of disposable absorbent articles such as diapers has
increased considerably in recent years owing to their ease of use,
low cost, and the advantage of having a clean, fresh, absorbent
article without the inconvenience of having to wash, store, fold
and re-use a previously used non-diposable article. The advantages
of using disposable absorbent articles are particularly apparent in
the wide acceptance of disposable diapers as a replacement for the
cloth diapers which have traditionally been used.
The invention will be described in detail with reference to a
disposable diaper, but the teachings herein are applicable to other
disposable absorbent articles such as incontinency pads and the
like.
Disposable diapers known to the art generally include a liquid
absorbing layer, a liquid impermeable backsheet, and a hydrophobic
liquid permeable body contacting topsheet. The liquid absorbent
layer is generally an absorbent material having a high degree of
absorption properties. The absorbent materials can be tissue paper
or wadding stacked to the desired thickness, or wood pulp products
such as wood fluff. It has been proposed, for example in Belgian
Pat. No. 752,366, to employ as the liquid absorbent material a film
of an insoluble hydrogel. A hydrogel is a hydrophilic,
water-insoluble polymer such as irradiated polyethylene oxide,
polyvinyl pyrrolidone, polyacrylic acid, and the like. Such
hydrogel films are particularly interesting for use in disposable
absorbent articles because, as mentioned previously, they are
capable of absorbing a very large amount of aqueous liquid.
However, the rate, as contrasted to the quantity of liquid absorbed
by such hydrogel film is, relative low. As a result, when, for
instance a baby wets, the hydrogel film does not absorb the urine
fast enough to prevent pools of urine from forming, which can cause
leakage around the edges of the diaper, as well as causing the baby
to be uncomfortable because of the wetness next to the skin.
In order to prevent such pool of urine from forming when a hydrogel
film is employed as the absorbent material in a disposable diaper,
I tried providing pinhole openings in the film which would permit
the passage of urine to the side of the film away from the baby, to
thereby keep the moisture away from the baby's skin until the
hydrogel film has had a chance to absorb it. However, when pinholes
were employed as the openings in the film, it was found that as
soon as the film absorbed moisture, the pinholes swelled shut and
no longer permitted passage of liquid to the backside of the film.
I then attempted to employ relatively long slits, for instance, 1/2
inch slits, in the film for this purpose. Unfortunately, however,
when the film absorbed moisture the slits did in fact open up to
permit passage of liquid therethrough, but the slits opened to such
wide openings that the liquid flowed right back from the other side
to the front again. This occurred even though an auxiliary layer of
hydrophilic absorbent material was placed on the side of the film
adjacent to the backsheet.
It has been discovered that the foregoing disadvantages in the use
of hydrogel film in a disposable article such as a diaper can be
significantly and substantially alleviated by employing a hydrogel
film having straight slits of controlled length. The slits that are
employed in the hydrogel film are of a magnitude such that when the
film absorbs liquid, the slits form openings which permit passage
of urine from the body contacting side of the diaper to the other
side of the film. Thus, pools of liquid (urine) on the side of the
film facing the baby's skin are avoided. When the film is
saturated, these slits tend to close thereby reducing the flow of
liquid back through the film to the side facing the baby's skin.
Optimum results are obtained when a secondary absorbent layer is
employed on the side of the hydrogel film adjacent to the
impermeable backsheet.
It is therefore an object of the present invention to provide an
absorbent article containing a hydrogel liquid absorbing sheet
material with controlled length slitted openings and having a high
degree of absorption properties.
Another object is to provide a disposable diaper having a hydrogel
film as the liquid absorbing material and which has been treated so
as to permit some liquid to pass through said hydrogel film during
periods of excessive flooding.
These and other objects will become apparent from the following
description of the invention taken in conjunction with the
accompanying drawings in which:
FIG. 1 is a perspective view of a disposable diaper constructed in
accordance with the principles of the invention;
FIG. 2 is a sectional view taken along line 2--2 of FIG. 1; and
FIG. 3 is a top view of a slitted hydrogel film suitable for use in
the invention, wherein part of the film has been wetted to
illustrate the opening up of the slits that occurs when the film
absorbs moisture.
In its broadest aspect the invention provides a disposable
absorbent article for placement adjacent to the body,
including:
a. a hydrophobic liquid permeable topsheet for placement adjacent
to the body;
b. a liquid impermeable backsheet; and
c. a hydrophilic, substantially water insoluble film disposed
between the topsheet and the backsheet. The film contains a
plurality of short slits, i.e., 1/16 to 3/8 inch in length, so that
aqueous liquid contacting the film causes the film to swell and to
thereby open the slits to permit passage of liquid
therethrough.
In a more specific aspect the invention provides a disposable
diaper including:
a. a hydrophobic liquid permeable topsheet for placement adjacent
to the body;
b. a liquid impermeable backsheet;
c. a hydrophobic, substantially water insoluble film containing a
plurality of slits of from 2/16 to 5/16 inch in length disposed
between the topsheet and the backsheet; and
d. an absorbent pad disposed between said backsheet and said
hydrophobic film.
In a preferred embodiment, two absorbent pads are utilized, one on
each side of the hydrogel material.
Referring to FIGS. 1 and 2 of the drawing which depicts the
absorbent article as a disposable diaper, it will be seen that the
diaper 10 includes a hydrophobic, liquid permeable body contacting
topsheet 11, a slitted hydrogel film 15, and a hydrophobic, liquid
impermeable backsheet 19. Also, in a preferred aspect of the
invention, the diaper contains secondary absorbing layers 13 and
17, containing a liquid absorbing material.
The topsheet layer of the disposable diaper of the invention is a
hydrophobic, liquid permeable layer. The topsheet can be, for
instance, an open celled foam layer, a loosely woven or a loosely
packed non-woven fibrous layer, a gauze, or a slitted hydrophobic
film, particularly an ethylene-ethyl acrylate copolymer film, such
as disclosed in copending application "Disposable Absorbent
Articles" by Theodore F. Kozak, Ser. No. 312,131 filed on Dec. 4,
1974, now U.S. Pat. No. 3,814,101, and assigned to the same
assignee as this application.
The topsheet should be thin, flexible, self-supporting, liquid
permeable or treated to make it selectively liquid permeable.
The backsheet 19, is a liquid impermeable layer or sheet and is
preferably an olefinic or vinyl film. Polyethylene of a thickness
of from about 0.4 to about 1.5 mils is most preferred. This type of
film has previously been used extensively for this purpose and
commonly has had an embossed design in its surface to simulate the
appearance and hand of cloth.
As depicted in FIG. 2, the disposable diaper 10 includes a hydrogel
film 15 between the topsheet layer and the backsheet layer. The
film is of the type that is known to the art, and is somtimes
referred to as a "hydrogel." Such hydrogels include polyvinyl
pyrrolidone, irradiated polyalkylene oxide, polyacrylic acid, and
mixtures thereof. The preferred hydrogel film is composed of
irradiated polyethylene oxide, polyacrylic acid, and mixtures
thereof. The preferred hydrogel film is composed of irradiated
polyethylene oxide such as is disclosed in U.S. Pat. No. 3,264,202.
Such irradiated polyethylene oxide is produced by subjecting an
aqueous solution of an ethylene oxide polymer having a molecular
weight of greater than about 100,000 and up to, for example, about
10,000,000, to ionizing radiation for a period of time and under
such conditions to form a substantially water insoluble hydrophilic
polymer. For use in the present invention, the hydrogel is
preferably produced in a film thickness of from about 0.5 to about
2.0 mils.
As will be seen in FIG. 3, the hydrogel film contains a plurality
of short slits. When the film absorbs moisture, the slits open up
to eye-shaped openings. These openings permit aqueous liquid such
as urine to readily pass through the film, from the side facing the
topsheet to the other side facing the backsheet. During periods of
excessive flooding localized pools of urine would normally build up
on the side of the film facing the topsheet if no slits were
present due to poor rate of absorption of the film. However, by
providing controlled slit lengths, the slits prevent the liquid
from passing back through the slits from the side facing the
backsheet to the side facing the topsheet. In order to accomplish
this purpose, the length of the slits must be carefully controlled.
It has been found, for example, that slits having a length of from
about 1/16 to about 3/8 inch, and preferably from about 2/16 to
about 5/16 inch, are highly desirable for accomplishing this
purpose. In general, the hydrogel film contains from about 2 to
about 24 slits per square inch of film area, and preferably from
about 4 to about 10 slits per square inch. The slits can be formed
in the film by any convenient means such as by piercing with a
sharp edge.
The preferred method for forming the slits in the hydrogel film
according to the present invention is described in U.S. Pat. No.
3,762,255 issued on Oct. 2, 1973 and entitled "Method and Apparatus
for Piercing Thin Sheet Material." Briefly, there is disclosed
therein a method and apparatus for piercing thin sheet material,
such as plastic film, wherein the sheet material is passed between
a piercing member having a plurality of independently resilient
protrusions extending therefrom and a backing member having a
retiform exterior surface. The piercing member or backup member is
moved relative to the other member, thereby causing the resilient
protrusions to follow the retiform surface and selectively pierce
the film. The piercing member can be a metal comb, a wire brush or
a metal strip having a plurality of substantially parallel slits
extending from one edge thereof in the direction of the opposite
edge defining the resilient protrusions. The backing member can be
a wire screen, a perforated metal sheet, an engraved metal roll or
an endless belt which is driven longitudinally with respect to the
piercing member.
As mentioned previously, the slits of controlled length in the
hydrogel film open when wet to permit excess liquid to flow through
the film to the backsheet. This is best illustrated in FIG. 3 which
is a top view of a slitted hydrogel film suitable for use in the
disposable diapers of the invention. Thus referring again to FIG.
3, it will be seen that the film 15 contains a plurality of slits
21. The film has been wetted in an area generally designated as 23.
It is noted that the slits 21 in the wetted area 23 have opened to
eye-shaped openings. It is especially interesting to note that
where a slit 21 crosses the interface from the dry area of the film
15 to the wet area 23, that the portion of the slit 21 in the dry
area remains closed, whereas the portion of the slit in the wetted
area has opened to an eye-shaped opening 25.
In a preferred embodiment of the invention, the disposable diaper
of the invention may optionally have additional moisture absorbing
layers. For instance, a relatively thin moisture absorbing layer
composed of, for example, cellulose tissue, or the like, can be
interposed between the topsheet and the hydrogel film. Another
layer of moisture absorbing material can be interposed between the
backsheet and the hydrogel film. The purpose of the two secondary
absorbing layers, and particularly the absorbing layer that is
interposed between the backsheet and the hydrogel film, is to
temporarily absorb moisture that passes through the slits in the
hydrogel film until the hydrogel film has had an opportunity to
absorb the moisture.
Absorbent materials other than cellulose tissue will, of course, be
useful in the construction of the present invention. For example,
absorbent non-woven pads can be fabricated to any desired thickness
and substituted for the cellulose tissue layer described above. One
such absorbent layer or pad which has been used extensively in
disposable diapers is a wood pulp product commonly known as wood
fluff and is prepared in the same manner as a non-woven fabric.
Thus such type absorbent pad is also useful as the absorbent pads
of the inserts of the present invention.
Various natural and synthetic polymeric materials are themselves
absorbent or can be made absorbent and will therefore be useful as,
or in combination with, the absorbent layer of the present
invention.
The only criteria for utility in the present invention are that the
material constituting the absorbent layers be absorbent, be capable
of being fabricated in the form of a pad, be compatible with the
waste products with which it will come in contact and be
non-irritating to the skin.
The fabrication of the diaper may be accomplished by a variety of
techniques. In a preferred technique, the topsheet and backsheet
are cut to approximately the same dimensions which are equal to the
desired size of the final diaper.
The topsheet and backsheet are then juxtaposed one on the other
with the hydrogel film sandwiched therebetween in approximately the
center of the sheets. The hydrogel film should be of a length and
width slightly smaller than the topsheet and backsheet to permit
sealing of the topsheet to the backsheet around their periphery. An
overhang of about one-half inch on each side should be sufficient.
In addition, the hydrogel film is slitted according to the
previously explained procedure prior to fabrication to the diaper.
Sealing can conveniently be accomplished such as by the use of an
adhesive or if both sheets are thermoplastic, then by heat sealing
the edges.
In the case where one or more absorbent pads are utilized in
conjunction with the hydrogel film, then the pads may be
superimposed on the hydrogel film and assembled into the diaper as
explained previously.
* * * * *